#12876: Fix element and parent classes of Hom categories to be abstract, and
simplify the Hom logic.
----------------------------------------------------------------------------------------+
Reporter: nthiery
| Owner: nthiery
Type: enhancement
| Status: needs_review
Priority: major
| Milestone: sage-pending
Component: categories
| Resolution:
Keywords: categories, Hom
| Work issues:
Report Upstream: N/A
| Reviewers: Simon King
Authors: Nicolas M. Thiéry
| Merged in:
Dependencies: #715, #11521, #12215, #12313, #13412, #13145, #14159, #13184,
#14287 | Stopgaps:
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Comment (by SimonKing):
I have
{{{
> hg qa
trac_14159_weak_value_triple_dict.patch
trac_14159_use_cdef_get.patch
trac_13184_sage_5.9.beta.patch
trac_14287-rebased.patch
trac_12876_category_abstract_classes_for_hom.patch
trac_12876_r_test.patch
}}}
on top of sage-5.9.rc0, and the relevant lines in
sage/categories/schemes.py are
{{{
"""
return []
class ParentMethods:
def __new__(cls, R, S, category):
"""
TESTS::
sage: E = EllipticCurve('37a1')
sage: Hom(E, E).__class__
<class
'sage.schemes.generic.homset.SchemeHomset_generic_with_category'>
If both schemes R and S are actually specs, we want
the parent for Hom(R, S) to be in a different class::
sage: Hom(Spec(ZZ), Spec(ZZ)).__class__
<class
'sage.schemes.generic.homset.SchemeHomset_points_spec_with_category'>
Currently, and to minimize the changes, this is done
by delegating the job to SchemeHomset. This is not
very robust: for example, only one category can do
this hack.
FIXME: this might be better handled by an extra Spec
category
"""
from sage.schemes.generic.homset import SchemeHomset
return SchemeHomset(R, S, category=category)
#############################################################
}}}
However, the patch expects
{{{
"""
return []
- class ParentMethods:
-
- def __new__(cls, R, S, category):
- """
- TESTS::
-
- sage: E = EllipticCurve('37a1')
- sage: Hom(E, E).__class__
- <class
'sage.schemes.generic.homset.SchemeHomset_generic_with_category'>
-
- If both schemes R and S are actually specs, we want
- the parent for Hom(R, S) to be in a different class::
-
- sage: Hom(Spec(ZZ), Spec(ZZ)).__class__
- <class
'sage.schemes.affine.affine_homset.SchemeHomset_points_spec_with_category'>
-
- Currently, and to minimize the changes, this is done
- by delegating the job to SchemeHomset. This is not
- very robust: for example, only one category can do
- this hack.
-
- FIXME: this might be better handled by an extra Spec
category
- """
- from sage.schemes.generic.homset import SchemeHomset
- return SchemeHomset(R, S, category=category)
#############################################################
}}}
So, what tickect changed
`sage.schemes.generic.homset.SchemeHomset_points_spec` into
`sage.schemes.affine.affine_homset.SchemeHomset_points_spec`?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12876#comment:126>
Sage <http://www.sagemath.org>
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